Tall Evergreen Hedges The Gardener (2023)

Tall Evergreen Hedges

Surrounding your garden with an imposing hedge is like planting a ‘neighbour’ you have chosen yourself and like a lot!

You would not normally associate a tall and formally pruned privacy hedge with a moderately sized or small suburban garden, but it is quite possible to train a row of large evergreen shrubs and even small upright-growing trees into a dense and enveloping screen up to 2.5m high (or as high as a regular ladder might comfortably reach) and with a width of only 1m or less. Any higher or wider can become a nuisance, as very tall hedges can cause too much shade and are normally supported by vigorous roots competing against those of other plants.

Planting a row of camphor bushes (Tarchonanthus camphoratus) along the ugly wire fence of my small front yard was one of the best decisions I have ever made.

The advantages:

The plants were much, much cheaper than the quotes I received for even the most basic solid boundary wall. The choice of plant was correct, as it suits a dry and windy coastal climate where water restrictions are often a reality – you seldom irrigate the hedge in the background as regularly as you would do other plants.

It is also known as a hasty grower that tolerates pruning to encourage a dense, albeit a less ‘natural’, growth form. Within a short period, the plants that arrived in small 4-litre nursery bags had created a serene green corridor between me and the neighbouring property, in which the birds love to flutter and even nest in. Whereas my side is often cut formally to keep it in check, the neighbour leaves his side of the hedge’s branches escaping through the wire fence, mostly uncut so that we and the wildlife can enjoy a flowering phase. This symbiosis along the fence seems to work well, although it is obviously not the norm as far as formal hedging is concerned! (I have to mention this as you should definitely consider your neighbour when planning a very tall hedge. It could affect the microclimate in their garden too.)

My hedge, which is part of a wide shrub bed, also created a good backdrop for the other plants that I planted in the foreground and successfully blocks out the prying eyes of leisurely strollers in the street. It has turned my garden into an intimate space.

Fabulous favourites

When choosing tall hedge plants to define borders and boundary lines, keep in mind that they should be evergreen with a naturally upright and dense growth habit. They should also tolerate regular pruning. You need not forfeit the flowers on those that flower in specific seasons; as it is simply a matter of knowing when to do a good prune and when to wait around a bit.

Here are a few trustworthy tall hedges or screening plants:

Syzygium paniculatum (eugenia)

• A very popular evergreen hedge plant with dense foliage and a rapid growth rate, it will reach up to 4m in height if left unchecked.
• It has a natural pyramid shape and attractive fresh green, small leaves.
• Great choice for small gardens that need plants that can provide height in a restricted space, as the shallow root system does not damage structures.
• Creamy powder-puff flowers appear early in summer, followed by edible dark pink fruit.
• Eugenias are sensitive to extreme cold and frost.
• Any soil type will do, but good drainage and compost-enriched soil will ensure lush plants.
• Watering requirements are medium, and a frequent dose of nitrogen-rich fertiliser in spring and in late summer is recommended.
• On a cautionary note: densely growing eugenia hedges can often become infested with aphids that secrete a sticky black substance called honeydew. This spoils the hedge’s good looks and attracts ants, which in turn spread the aphid eggs to other plants. To curb this, use a systemic soil drench like Koinor annually around the plants. This will ensure prolonged protection from aphids.

Pruning tricks: Unless you want to use the fruit to make jelly, rather prune a eugenia hedge regularly to encourage a dense hedge. You can even go as low as 1m if a high hedge is not what you need.

Viburnum tinus ‘Lucidum’ (laurustinus)

• Evergreen with a naturally dense growth habit to use as a windbreak or for noise reduction, with a mature size of between 2 – 4m high and 1 – 2m wide, depending on the climate.
• Fast-growing, with at least 40 – 60cm growth per year.
• The leaves are oval and mid- to dark green.
• Tight pink flower buds appear in late winter, opening up into flat flowerheads of softly fragranced, small white flowers followed by red and bluish-black berries.
• This sun-loving shrub will also tolerate partial to even full shade, and any soil type will do.

Note: Another good choice to consider is Viburnum odoratissimum (sweet viburnum), which has the same growing requirements but slightly bigger, mid-green leaves.

Pruning tricks: It can be formally and regularly pruned at any time of the year, but if you want to see some flowers give it a breather from late autumn, as it will start blooming in late winter, before giving it another haircut in early summer. If a viburnum hedge is ailing for some or other reason, you can prune it back quite hard as it generates new growth from old wood.

Cupressus x leylandii (Leyland cypress)

• Very popular conifer that is used mainly for hedging and screening the world over.
• It is a smart and stately evergreen with a tapering growth habit and sprays of dark green needle-like foliage. It is also a good nesting and sheltering plant for birds.
• Although the root system is shallow, it can be far-reaching – controlling this giant’s natural height will inhibit its size below ground too. Care should be taken not to plant a Leyland hedge too close to buildings.
• Growth is fast and can be up to 1m per year, which means that a Leyland hedge would need trimming at least 2 – 3 times a year.
• It will grow in any soil type with good drainage. Since root disease and aphids can sometimes cause problems, it is recommended that the hedge be treated preventatively at soil level with systemic products every year.
• Established Leyland cypress trees are quite resistant to drought, wind, cold and frost.

Pruning tricks: Since conifers grow actively in the cooler months, the sides of a hedge should then be trimmed lightly to encourage denseness, but never too hard or beyond green foliage. Topping the hedge to control its height would cause no damage.

Brachylaena discolor (coast silver oak)

• Dense and spreading multistemmed evergreen tree that naturally branches out low down.
• This fast grower can reach a height of 8m or more in a garden, but can easily be trained into a dense screening hedge.
• The foliage is very showy with a dark green, leathery and glossy sheen on top and a silvery-white
• flipside.
• Masses of nectar-rich creamy white flowers in terminal panicles appear from late winter to spring.
• The root system is non-invasive and the plant is extremely resistant to drought, wind and frost.
• It will grow well in full sun or shade and will tolerate heavy clay soil.

Pruning tricks: If pruned formally (which is recommended to tame its width and height), allow the top of the hedge to remained unpruned from early autumn to enable you and the bees to enjoy some flowers during winter. Prune back at the end of September.

Photinia x fraseri ‘Red Robin’ (Christmas berry)

• A fantastic screening plant with a natural height of between 3 – 6m depending on growing conditions. • It is relatively fast growing and not fussy about soil type.
• Its best attribute is young leaves that are reddish to coppery orange in colour, turning to vibrant bronze before maturing into glossy dark green.
• Panicles of white flowers appear in summer and are followed by dark fruits loved by birds.
• ‘Red Robin’ is cold and frost hardy.

Pruning trick: To enjoy a coppery ‘head’ on your hedge you can sometimes leave the top of the hedge unpruned from late winter to spring, before shaping it more formally again after the leaves have turned green. If an old photinia hedge is not looking well due to neglect, it can be severely cut back to knee-high in spring without any fear of killing it.

Tall hedging in a nutshell

1. The shape should be narrower at the top and wider at the bottom, like an upside-down V. This is done to allow the maximum amount of light to reach the whole area of the plant, which will ensure density.

2. Don’t be intimidated by pruning. It is simply a case of using shears with long scissor-like blades or a power or battery-operated trimmer to take off branch tips to stimulate new buds. If anything more drastic is needed, it means that the hedge has been left to its own devices for too long.

3. Spacing distance?

This is a tough one to work out, but since you need filling in as fast as possible, planting should be between 60cm and 1.2m apart, depending on the plant choice.

4. How to obtain a perfectly geometric and straight hedge:

• Digging a trench when planting a hedge goes a long way to ensure that a hedge is straight. Soil preparation in a trench, with ample compost and root fertiliser to sustain the fast-growing plants, can be achieved far more easily than in individual planting holes.

• Precision cutting can be done by running a string line between stakes to ensure an even line, but rather relax and trust your eyes and gut feel. It works well once you realise that spending time shaping your hedge can be very therapeutic…